nokia 4A0-255 Exam Questions
Questions for the 4A0-255 were updated on : Nov 21 ,2025
Page 1 out of 3. Viewing questions 1-15 out of 40
Question 1
Which of the following statements about the management plane data Communications Network
(DCN) is correct?
- A. The management plane DCN uses in-band communication.
- B. The management plane DCN can be connected to each NEs via OSS/OBS interface.
- C. The management plane DCN can be connected to each NEs directly.
- D. The management plane DCN enables direct communication between the NEs.
Answer:
C
Question 2
Which of the following can be detected through power monitoring with an Optical Time Domain
Reflect meter?
- A. Intrusions on fibers
- B. Power injection one channel
- C. Hacking of L1 encryption
- D. Intrusions in the cryptographic keys
Answer:
B
Question 3
Which of the following is recommended to reduce the latency of a 30km long link?
- A. DCM-free amplifiers
- B. Soft-decision FEC
- C. Low-noise amplifiers
- D. L1 encryption
Answer:
C
Question 4
Suppose that for a given number of buffer credits and for an given average FC frame size, the
maximum FC link length is 50 km.
If the average FC frame size is doubled, which of the following is correct?
- A. The throughput is halved.
- B. Throughput is doubled.
- C. The Throughput is the same,.
- D. The buffer credits need to be adjusted to achieve the maximum throughput.
Answer:
D
Question 5
What is precision Time Protocol (PTP) designed for?
- A. Precise time measurements
- B. Synchronization of encryption entities
- C. Shortest path discovery
- D. Packet-based timing distribution
Answer:
B
Question 6
Which if the following statements about Recovery Time Objective (RTO) and Recovery Point Object
Point Objective (PRO) is FALSE?
- A. RTO/PRO define business continually requirements for data center.
- B. RTO/PRO defined the acceptable amount of data (in bits) that can be lost after a failure.
- C. Data center mirroring has the most critical level of RTO.RPO among DC applications.
- D. Tier ½ data centers have stricter RTO/PRO requirements than Tire ¾.
Answer:
B
Question 7
Which of the following statements about an alien wavelength at 10G is correct?
- A. It is an optical signal generated by FWM impairment.
- B. It has similar optical performance across multiple vendors equipment at 10G.
- C. It can be measured by a VAC card.
- D. It does not support Wavelength tracker.
Answer:
B
Question 8
Which of the following statements about the recovery time for protection and restoration combined
(PRC) is correct?
- A. PRC can be as fact as sub-network connection protection (SNCP)
- B. PRC is as fast as restoration mechanisms.
- C. PRC has a recovery time that depends on the broken links.
- D. PRC has a typical recovery time greater than 50 ms.
Answer:
B
Question 9
Which of the following statement about guaranteed restriction (GR) in generalized Multiprotocol
label Switching (GMPLS) is correct?
- A. GR use reestablished backup LSPs with resources reserved and configured.
- B. GR can achieve 100% survivability for a single-failure scenario only.
- C. GR does not required the signaling of the fault to trigger the restoration.
- D. GR calculates a new backup LSP every time a failure occurs.
Answer:
A
Question 10
Consider an OTN-based network controlled by GMPLS. Which of the following statements is correct?
- A. An OCH LSP can be routed through an ODU LSP.
- B. An ODU LSP can be routed through an OCH LSP.
- C. An ODU LSP is routed between two photonic layer nodes.
- D. The routing of the individual ODU frames is based on their label
Answer:
D
Question 11
Consider the exhibit that shows the OTN frame structure . Which of the following sets of label is
correct?
- A. OUT: B: ODU: C: OPU: D: OPU
- B. OUT: B: ODU: C: OPU: D: OCH
- C. OPU: B: OTU: C: ODU: D: OPU
- D. ODU: B: OYU: C: OPU: D: OPU
Answer:
C
Question 12
Consider the exhibit. Which of the following NE architectures is represented?
- A. TOADm
- B. (Classic) ROADM
- C. C-F ROADM
- D. CDC-F ROADm
Answer:
A
Question 13
Consider the exhibit. Which type of survivability mechanism is selected for this trail?
- A. Source-based restoration.
- B. Guaranteed restoration
- C. Optical sub-network connection protection
- D. Protection and restoration combined
Answer:
A
Question 14
What does an OPU tributary slot contain, when multiplexing OTN frames?
- A. An OUT.
- B. An ODU.
- C. An OPU.
- D. An OH byte
Answer:
C
Question 15
Consider the exhibit, where the two highest ports are OT line ports. Which of the following
statements is correct?
- A. The OCH protection is implemented.
- B. The O-SNCP protection is implemented.
- C. The E-SNCP protection is implemented.
- D. An OPS is required upstream (left of the OT).
Answer:
D